War and social injustice provoked Martha Gellhorn. Ernest Hemingway, her onetime husband, wrote, ''She is at her best when angry or moved to pity.'' Born in 1908 into a politically conscious family in St. Louis, Gellhorn dropped out of Bryn Mawr and moved to New York to begin her writing career. Short, unfulfilling editorial stints and wanderlust led her to leave the United States in 1930, and she never again considered it her home. Writing for Collier's and other magazines, Gellhorn led an itinerant life, covering the Spanish Civil War, World War II and the Vietnam War. Before her death in 1998, she published more than 100 articles and 16 books -- fiction, journalism, a travel memoir -- and a play. Carl Rollyson, the author of books on Susan Sontag and Rebecca West, devotes most of ''Beautiful Exile'' to Gellhorn's five years with Hemingway, her second husband, and to her war reportage. Her life story becomes a study in the influence of the right connections on a career: Gellhorn landed a New Deal job through her friendship with the Roosevelts, procured a foreword from her onetime lover H. G. Wells and had Hemingway do her bidding with their shared editor. In her own words, ''the blonde bit was what always confused the issue: luscious blonde or serious writer?'' Although an interesting glimpse at Gellhorn's life, the narrative remains superficial, perhaps a tribute to Gellhorn's refusal to help unauthorized biographers. Shannon Brady Marin